Telephone receiver



July 13, 1937. W 2,086,630

TELEPHONE RECEIVER Filed June 9, 1934 Fla. 2

IN l/E N TOR RCM/NER 8) ATTORNEY Patented 1.1, is, 1931 I PATENT OFFICE TELEPHONE RECEIVER Russell 0. Miner, Summit, N. 1., assignor to Bell Telephone Laboratories, Incorporated, New

York, N. Y., a corporation of New York Application June 9. mar, Serial No. 729,762

This invention relates to telephone receivers and particularly to that type of receiver known as a bone' conduction receiver wherein vibrations produced thereby are transmitted to the 5 auditory nerve through direct contact between the vibratile element of the receiver and a portion of the bony structure of the head of'the user.

The object of this invention is to provide a bone 7 l conduction receiver which is light, small, ef-

flcient and rugged and yet inexpensive.

In its preferred form this invention comprises a casing to which is rigidly secured an armature and a resilient member, and a pair of electro- 16 magnets secured to the resilient member and held in close spaced relation to the armature thereby. The pole-pieces employed are fabricated of two L-shaped members and a plate welded or otherwise secured togethepto form a T, and the ends of the cross-bars of the T are connected by parallel bar permanent magnets. Thecoils of the electromagnets are mounted with their axes at right angles to the cross-bars and permanent magnets and the tails of the 'Ts are accordingly notched and shaped to form the cores of the electromagneta This construction of the electromagnets results in a very compact and emcient receiver.

For a better understanding or .the invention reference is made to the accompanying drawing in which:

Fig. 1 is a plan view of the receiver with the cover removed to show the compact arrangement of the electromagnets;

35 Fig. 2 is an elevation of the receiver sectioned along line 2-2 of. Fig. l; and

, Fig. 3 is an exploded view oithe magnet structure'used in the receiver.

Referring more particularly now to Figs. 1 and 2, I0 is a casing, preferably made of a phenol plastic composition, of which I I forms a cover. The cover II also serves as the vibration-conducting member of the receiver, and its surface therefore may be curved or otherwise formed to take the shape of a particular portion of theusers head, such, for example, as the mastoid process, to increase the area of the conducting surface in contact with the head and thereby increase the efflciency of the receiver. Shaping the contact- 0' ing surface'to the user's head also tends to reduce the unit pressure upon the head, which makes" the receiver more comfortable to use.

. An armature l2 and a. U-shaped spring member.

or yoke, I3 are secured to cover II by means of a rivet II. The eiectromagnets and polarizing 3 Claims. I (CL-179-10'l) I magnets used in the receiver are suspended from cover II by attachment to resilient member II.

The novel construction of the magnets is best described with reference to Fig. 3. The cores of the electromagnets are comprised of two 6 L-shaped members I! and I 6 and a plate l'l secured together, preferably by spot welding, to form a unit in the form of a T. Prior towelding, the L-shaped members are notched with a rectangular notch l8 to form a core I! perpen- 10 dicular to the face of the T, on which a coil 20 (shown in Fig. '3 by dotted lines) may be mounted. All three members of the core unit may thusbe stamped out and formed on a punch press and united by spot welding, which constructiog is much less'costlythan a single piece construction would be since the latter. due to the peculiar shape of the unit, would necessitate several milling operations and would result in a waste of a large amount of material.

The cores are placed with the long axes of the cross-sections thereof in line instead 01 parallel to one another as is the common practice. This permits the width of the receiver to be considerably. reduced and causes the cross-bars of the T-shaped units to assume a parallel position. The ends 01' the cross-bars are then connected to permanent bar magnets 2i, preferably by soldering the ends thereto, to form a unified whole, resembling, when viewed as in Fig. 1, a rectangle within which the electromagnets are supported by extensions from the smaller sides of the rectangle. The magnet structure is thus exceedingly compact and yet contains a sufllcient quantity of magnetic material properly to carry 35 out the functions of the receiver.

The care units are drilled and tapped at 22 to receive machine screws 23 (Figs. 1 and 2) by which the magnet structure is secured to resilient yoke ii. The cores l9 and armature I! are thus held in close spaced relation to one another without freezing".' Suitable flexible leads" and 24 connect coils to sleeves 25 and 28 respectively whereby electrical contact may be established between the electromagnets and an external 45 electrical circuit.

' For best results the T-shaped units and armature l2 should be made of a material commonly j known as permalioy and containing approximately nickel, 0.60% cobalt, 0.05% carbon and the balance iron. The permanent magnets should be made of a cobalt steel the contents of which are approximately 36% cobalt, 7% tungsten, 3.50% chromium, 0.75%. carbon and the balance iron.

When the receiver is in operation, due to the inertia of the magnet structure and its resilient mounting within the casing, the entire casing is vibrated and the vibrations thus produced may readily be transmitted to various parts of the body merely by contact therewith. When used with the mastoid process, a headband may be employed to hold the receiver in place. For this purpose, the sides of the receiver are apertured as;

at 2 1 to receive the headband. If the receiver is to be used with other parts of the body. a handle, similar to a lorgnete handle (not shown) may be provided upon which to mount the receiver.

If desired the portion of the device to be held in contact with the mastoid eminence or other portion of the body of the user may be contoured to fit theindividual user by molding processes well known to the surgical and dental professions.

It is understood that the above description is merely illustrative of the invention and that the scope of the invention accordingly should not be limited thereby but should be determined by the appended claims.

' What is claimed is: I

1. In a telephone receiver, an electromagnet comprising a coil and a magnetizable core there-.

pole-pieces, each pole-piece being comprised of the legs of alpair of L-shaped members, said polepieces being ,formed by notching said legs, and magnetizable bars connecting the free ends of the legs of the L-shap'ed members. 1

3. A bone conduction receiver comprising a rectangular casing, a U-shaped spring member secured to a side of the casing, an armature secured to the bottom of the U, electromagnets se cured to the ends of the U and permanent magnets connecting the electromagnets, each of said electromagnets being comprised of two L-shaped members and a plate spot-welded together to form a T, the tail of the T beingnotched at the side to form a core the axis of which is at right angles to the tail and cross-bar of the T, and the cross-bars of the Ts being connected by parallel permanent bar magnets to form a rectangular enclosure for the electromagnets.

RUSSELL c. MINER. 

